The invention relates generally to Therapeutic proteins (including, but not limited to, at least one polypeptide, antibody, peptide, or fragment and variant thereof) fused to albumin or fragments or variants of albumin. The invention encompasses polynucleotides encoding therapeutic albumin fusion proteins, therapeutic albumin fusion proteins, compositions, pharmaceutical compositions, formulations and kits. Host cells transformed with the polynucleotides encoding therapeutic albumin fusion proteins are also encompassed by the invention, as are methods of making the albumin fusion proteins of the invention using these polynucleotides, and/or host cells.
Over the past few decades, an increasing percentage of the population has become diabetic. Diabetes mellitus is categorized into two types: Type I, known as Insulin-Dependent Diabetes Mellitus (IDDM), or Type II, known as Non-Insulin-Dependent Diabetes Mellitus (NIDDM). IDDM is an autoimmune disorder in which the insulin-secreting pancreatic beta cells of the islets of Langerhans are destroyed. In these individuals, recombinant insulin therapy is employed to maintain glucose homeostasis and normal energy metabolism. NIDDM, on the other hand, is a polygenic disorder with no one gene responsible for the progression of the disease.
In NIDDM, insulin resistance eventually leads to the abolishment of insulin secretion resulting in insulin deficiency. Insulin resistance, at least in part, ensues from a block at the level of glucose uptake and phosphorylation in humans. Diabetics demonstrate a decrease in expression in adipose tissue of insulin-receptor substrate 1 (“IRS1”) (Carvalho et al., FASEB J 13(15):2173-8 (1999)), glucose transporter 4 (“GLUT4”) (Garvey et al., Diabetes 41(4):465-75 (1992)), and the novel abundant protein M gene transcript 1 (“apM1”) (Statnick et al., Int. J. Exp. Diabetes 1(2):81-8 (2000)), as well as other as of yet unidentified factors. Insulin deficiency in NIDDM leads to failure of normal pancreatic beta-cell function and eventually to pancreatic-beta cell death.
Insulin affects fat, muscle, and liver. Insulin is the major regulator of energy metabolism. Malfunctioning of any step(s) in insulin secretion and/or action can lead to many disorders, including for example the dysregulation of oxygen utilization, adipogenesis, glycogenesis, lipogenesis, glucose uptake, protein synthesis, thermogenesis, and maintenance of the basal metabolic rate. This malfunctioning results in diseases and/or disorders that include, but are not limited to, hyperinsulinemia, insulin resistance, insulin deficiency, hyperglycemia, hyperlipidemia, hyperketonemia, and diabetes.
Numerous debilitating diabetes-related secondary effects include, but are not limited to, obesity, forms of blindness (cataracts and diabetic retinopathy), limb amputations, kidney failure, fatty liver, coronary artery disease, and neuropathy.
Some of the current drugs used to treat insulin resistance and/or diabetes (e.g., insulin secratogogues—sulfonylurea, insulin sensitizers—thiazolidenediones and metformin, and α-glucosidase and lipase inhibitors) are inadequate due to the dosage amounts and frequency with which they have to be administered as a result of poor pharmacokinetic properties, the lack of effective control over blood sugar levels, and potential side effects, among other reasons. Diabetes Therapeutic proteins in their native state or when recombinantly produced exhibit a rapid in vivo clearance. Typically, significant amounts of therapeutics are required to be effective during therapy. In addition, small molecules smaller than the 20 kDa range can be readily filtered through the renal tubules (glomerulus) leading to dose-dependent nephrotoxicity.
Diabetes Therapeutic proteins in their native state or when recombinantly produced are typically labile molecules exhibiting short shelf-lives, particularly when formulated in aqueous solutions. The instability in these molecules when formulated for administration dictates that many of the molecules must be lyophilized and refrigerated at all times during storage, thereby rendering the molecules difficult to transport and/or store. Storage problems are particularly acute when pharmaceutical formulations must be stored and dispensed outside of the hospital environment. Many protein and peptide drug compositions also require the addition of high concentrations of other protein such as albumin to reduce or prevent loss of protein due to binding to the container. For this reason, many therapeutic proteins are formulated in combination with a large proportion of albumin carrier molecule (100-1000 fold excess), though this is an undesirable and expensive feature of the formulation.
Few practical solutions to the storage problems of labile protein molecules have been proposed. Accordingly, there is a need for stabilized, long lasting formulations of proteinaceous therapeutic molecules that are easily dispensed, preferably with a simple formulation requiring minimal post-storage manipulation.
Human serum albumin possesses many desirable characteristics. HSA is found throughout the body, but more specifically in the interstitial space and in blood at serum concentrations of 40 g/L which is equivalent to 0.7 mM (Yeh et al., Proc. Natl. Acad. Sci. USA, 89:1904-1908 (1992)). HSA is considered to be the most abundant protein of the serum and is responsible for maintaining osmolarity. HSA has favorable pharmacokinetic properties and is cleared very slowly by the liver displaying in vivo half-lives up to several weeks (Yeh et al., Proc. Natl. Acad. Sci. USA, 89:1904-1908 (1992); Waldmann, T. A., Albumin Structure, Function and Uses, pp. 255-273 (1977)). HSA lacks enzymatic activity and antigenicity thereby eliminating potentially undesirable side effects. HSA acts as a carrier for endogenous as well as exogenous ligands. Combined, these features can be extended, at least partially, onto albumin fusion proteins. The poor pharmacokinetic properties displayed by Diabetes Therapeutic proteins can then be circumvented.
Human serum albumin (HSA, or HA), a protein of 585 amino acids in its mature form (SEQ ID NO:327) of approximately 66 kDa, is responsible for a significant proportion of the osmotic pressure of serum and also functions as a carrier of endogenous and exogenous ligands. At present, HA for clinical use is produced by extraction from human blood. The production of recombinant HA (rHA) in microorganisms has been disclosed in EP 330 451 and EP 361 991.
The present invention is directed to albumin fusion proteins comprising a Therapeutic protein (e.g., a polypeptide, antibody, or fragment or variant thereof) fused to albumin or a fragment (portion) or variant of albumin. The present invention also encompasses polynucleotides comprising, or alternatively consisting of, nucleic acid molecules encoding a Therapeutic protein (e.g., a polypeptide, antibody, or fragment or variant thereof) fused to albumin or a fragment (portion) or variant of albumin that is sufficient to prolong the shelf life of the Therapeutic protein, increase serum half-life, and/or stabilize the Therapeutic protein and/or its activity in solution (or in a pharmaceutical composition) in vitro and/or in vivo. In one embodiment, an albumin fusion protein encoded by a polynucleotide described in Table 1 or 2 has extended shelf life. In a second embodiment, an albumin fusion protein encoded by a polynucleotide described in Table 1 or 2 has a longer serum half-life and/or stabilized activity in solution (or in a pharmaceutical composition) in vitro and/or in vivo than the corresponding unfused Therapeutic molecule described in Table 1 or 2. The present invention also encompasses polynucleotides, comprising, or alternatively consisting of, nucleic acid molecules encoding proteins comprising a Therapeutic protein (e.g., a polypeptide, antibody, or fragment or variant thereof) fused to albumin or a fragment (portion) or variant of albumin. Albumin fusion proteins encoded by polynucleotides of the invention are also encompassed by the invention, as are host cells containing these polynucleotides, and methods of making the albumin fusion proteins of the invention and using these polynucleotides, and/or host cells. The invention also encompasses polynucleotides encoding therapeutic albumin fusion proteins, therapeutic albumin fusion proteins, compositions, pharmaceutical compositions, formulations and kits.